Love hurts. And if you are nursing a broken heart this Valentine's Day, it won't help at all to learn that modern love hurts more now than ever. Women may have fled to nunneries and men marched to war over it, poets pined away, playwrights gone to jail for it, and Meatloaf promised to do anything for it, but experts believe love has never caused such acute suffering as it does now.

The blame lies with Hollywood, capitalism and the internet, all of which have caused mayhem in our love lives and taught us to behave like consumers when it comes to affairs of the heart. We treat looking for love as we would approach a buffet table, says sociologist Eva Illouz, in a new book being hailed as an "emotional atlas" for the 21st century.

Our relationship with relationships is now so chaotic that it touches every part of our psyche. Heartache is no longer contained in the heart and a growing army of psychologists and sociologists warn that love is in a perilous state. Modern marriage has been called "toxic", the changing roles between the genders are blamed for an upswing in divorce and an increasing focus on appearance is destroying the notion of a soulmate in favour of a sex mate.

But, according to Illouz, the reason is not the rise of feminism or dysfunctional childhoods, but instead down to us having too much choice – and too many commitment-phobic men.

In Why Love Hurts, Illouz, a sociologist at the Hebrew University of Jerusalem, attempts to explain the specific modern form of "romantic misery and happiness". She says our consumerist, capitalist culture has changed the face of our relationships beyond all recognition. The increasing choice from internet dating has encouraged people to act as "shoppers" – demanding, comparing alternatives, constantly trying to get a better deal and killing off the gut instinct and chance that has always helped humans to find a mate. Men have become commitment-phobes because the rise of capitalism has encouraged them to be autonomous and self-centred.

"Feminism has been so often blamed for the current disarray of romantic and sexual relationships," said Illouz, "that we have neglected to focus on the more immediate cause, capitalism. It has had a deep impact on the family: women defer childbearing because they prefer to develop careers provided by capitalist organisations. When they become mothers, most women keep working because work has become a part of self-fulfilment and because household expenditures now demand dual income.

"For men, marriage has become more optional. They don't need it. The romantic relationship has become more central to both men and women than ever and it's a great source of social worth, of validation. But men use sexual prowess, how many partners they have, to get a sense of worth, and women will want to be loved. So in that respect women are more dependent on men and want exclusivity while men want quantity."

The lack of harmony between the sexes is a growing concern.

"Men and women are definitely needing each other less as their roles converge," said Glenn Wilson, a fellow of the British Psychology Association and visiting professor at Gresham College, London. "I think the main change over the years is the Hollywood-driven belief that love and marriage should be contiguous – go together like horse and carriage. Because passion is short-lived, this results in our pattern of serial monogamy – repeated divorce and remarriage, leaving a trail of destruction.

"The other big change is that converging sex roles make marriage increasingly irrelevant. Who needs a partner if they don't bring complementary skill or responsibility to the union?"

Illouz says women who want children are in an even weaker position than in the past.

As any Jane Austen character could tell you, the people of the 19th century mostly married for economic and class reasons, says Illouz. Their relationships were ritualised to suit both genders, love and duty were intertwined and insecurity was nott in the picture.

"Why does Elizabeth Bennet, the heroine of Pride and Prejudice, greet Darcy's arrogant and dismissive comments about her appearance – 'she is tolerable but not handsome enough to tempt me' – with neither dejection nor with a sense of humiliation but rather with wit and spirit? Because his scorn doesn't shape or affect her sense of self and value.

"There is no conflict between their passions and their sense of moral duty and behaviour. So by modern standards Jane Austen's heroines are uncannily self-possessed and oddly detached from the need to be 'validated' or approved of by their suitors.

"Their sense of inner self is there and not changed by a man's view of them. So while women of that time were legally and economically dependent on men, they were absolutely not reliant on them." The modern situation is totally different, she says.

"By and large men and women are legally and intellectually equals. People think emotional difficulties between them are a remnant of the past but actually it's new – a change in the process of courtship.

"We have all these choices and think it's a type of freedom, but it's not. A complex menu of options is not necessarily freedom.

"Pre-modern people made a decision to marry based on a sense of social duty and convention. Modern people tend to do it out of a desire to realise our inner self, to be validated. Pre-modern people felt bound by a simple declaration of love; modern people prefer to keep their options always open, even after getting married."

Illouz said the situation was so dire that we ought to be thinking seriously about what might replace marriage as a method of raising children.

She is keen to stress that love is not over. "I wouldn't want to give the impression we have moved from total structure to total chaos. It's just that individuals now face a market of choices, a market of sex, and that can create great conflict and disconnect."